8 Replies Latest reply on Mar 3, 2014 6:04 PM by rob day

    Selective downsampling when exporting to PDF?

    PraxisCreativeArt Level 1

      Hi,

       

      I have a booklet with a number of pics in it. When I export such a job to PDF to create a print-ready version normally I'd just set it to downsample all images to 300 dpi, but in this case some of the pics are technical drawings with text and fine lines that I'd prefer to keep at a higher res - even up to 1200 dpi if possible (the drawings are large enough to provide this quality).

       

      So, is there a way of tagging individiual images in InDesign such that they won't be downsampled on export to PDF?

       

      Cheers,

      MP

        • 1. Re: Selective downsampling when exporting to PDF?
          Steve Werner Adobe Community Professional & MVP

          There's no way to tag individual images to not be downsampled when using PDF presets.

           

          Control the sampling yourself by doing it in Photoshop (you can use Actions or Image Processing). Then when exporting just choose Do Not Downsample and create a custom PDF preset.

          • 2. Re: Selective downsampling when exporting to PDF?
            PraxisCreativeArt Level 1

            There's no way to tag individual images to not be downsampled when using PDF presets.

             

            A pity, but many thanks for your rapid and helpful reply :-)

            • 3. Re: Selective downsampling when exporting to PDF?
              Laubender Adobe Community Professional & MVP

              @MP – there is a way to get the high-res images to the final PDF after you are downsampled the PDF. But this is a labor intensive process and requires Acrobat Pro and PhotoShop.

               

              There are also some restrictions.

              1. The PDF must not be flattened by  flattening transparency.

              PDF/X-4 as output would be ok with that. No PDF/X-3, no PDF/X-1a, if possible…

              2. You cannot use images with a clipping path

               

              Avoid to process, because some extra steps are necessary,

              3. If Images or their containers are rotated and/or sheared

              4. If the images are scaled unproportionally

              5. If images are cropped

               

              The process would be:

              Open the downsampled PDF in Acrobat Pro.

              Open PhotoShop with the original image in high-res quality.

               

              In Acrobat Pro use the TouchUp object Tool to open the low-res image in PhotoShop.

               

              In PhotoShop set the resolution of the downsampled image to the resolution of the original without changing its dimensions (width x height); in effect up-sample the image to its original values.

               

              Copy/Paste the pixels from the high-res original to the one opened from Acrobat Pro.

              Merge all layers to the background layer.

              Save and close the one opened from Acrobat Pro.

               

              It's clear that this process is labor intensive and could only be a workaround, if just a few images should maintain a very high resolution.

               

              And: it's highly debatable…
              Why not leaving all images at high-res?
              File size? No problem in  workflows nowadays, I think…

               

              Uwe

              • 4. Re: Selective downsampling when exporting to PDF?
                rob day Adobe Community Professional & MVP

                but in this case some of the pics are technical drawings with text and fine lines that I'd prefer to keep at a higher res - even up to 1200 dpi if possible (the drawings are large enough to provide this quality).

                 

                If you save the technical drawings as line art (Bitmap diffusion dither) then the export's Monochrome Images downsampling will be used.

                1 person found this helpful
                • 5. Re: Selective downsampling when exporting to PDF?
                  Laubender Adobe Community Professional & MVP

                  @Rob – good point!

                   

                  Uwe

                  • 6. Re: Selective downsampling when exporting to PDF?
                    PraxisCreativeArt Level 1

                    That’s a very good idea Rob, and one I'll file away for future use. I can't use it this time unfortunately - the tech drawings have colour in them.

                    • 7. Re: Selective downsampling when exporting to PDF?
                      PraxisCreativeArt Level 1

                      Laubender wrote:

                       

                      @MP – there is a way to get the high-res images to the final PDF after you are downsampled the PDF. But this is a labor intensive process and requires Acrobat Pro and PhotoShop.

                      Something of an understatement there Uwe.

                       

                      I did think of a slightly less convoluted way to achieve the same effect - create two PDFs, one complete at 300 dpi, a second with the subset of tech drawing pages at 1200 dpi. Then just replace 300 dpi tech drawing pages with 1200 dpi version. Fortunately there aren't too many so it won't take long.

                       

                      And: it's highly debatable…

                      Why not leaving all images at high-res?

                      File size? No problem in  workflows nowadays, I think…

                      Leaving the whole doc as very high res would be nice and easy, but my customer is not blessed with overly fast Internet connections (or a particularly well endowed laptop for that matter) and wouldn't be thanking me for sending what will end up being a tens-of-megabytes PDF

                      • 8. Re: Selective downsampling when exporting to PDF?
                        rob day Adobe Community Professional & MVP

                        but my customer is not blessed with overly fast Internet connections (or a particularly well endowed laptop for that matter)

                         

                        How is it being printed–offset? Many commercial printers will downsample at output, so you want to communicate with the printer to make sure that doesn't happen.

                         

                        Also if the color is RGB the black lines will convert to 4-color black at output, which might be a bigger problem than resolution.